This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present invention. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
While the task of well path planning is primarily an engineering function, a high-degree of geosciences, engineering integration and collaboration is involved during the planning process to achieve optimal results. In general, existing work processes and software tools lack the dynamic data integration capabilities required for interactive, cross-functional analysis and field development and management decisions.
Planning oil and gas wells involves designing well trajectories to optimally penetrate reservoir intervals while avoiding possible drilling hazards (e.g. shallow gas-bearing sands), and maximizing borehole stability and cost-effectiveness given the properties (e.g. temperature, stress, fluid pressure) of the stratigraphic column between the surface location and drilling targets. Current well design practices are often sequential, inefficient, and lack the tools and interactivity to adequately optimize a well design given a complex and uncertain three-dimensional distribution of possible reservoir intervals and drilling obstacles (hazards).
For example, a typical well planning workflow employing known technology may select potential subsurface targets. Potential targets are selected by a geoscientist based on a geologic interpretation and understanding of reservoir properties. Historically, this target selection step has been done using two-dimensional maps of reservoir horizons (e.g. base or top reservoir). More recently, to facilitate collaborative work practices and the visualization and evaluation of complex well designs, target selection may be done within a three-dimensional visualization environment. A drawback of existing three-dimensional visualization techniques is that they generally lack sufficient data to provide satisfactory results. For the purposes of well trajectory creation, target locations selected during this step are represented by points in three-dimensional space, each single point defined using an (X, Y, Z) coordinate to represent a target location. To assess the feasibility of the proposed targets, a three-dimensional visualization environment such as (for example, Gocad by T-Surf, Petrel by Schlumberger, or the like) may be used by a geoscientist and/or a drilling engineer to create a preliminary well trajectory based on the selected target points and user-defined screening-level constraints on the geometry of the well trajectory (e.g. dog-leg severity, also referred to as DLS). In cases where the initial target points are determined to be unacceptable, target locations can be removed or modified until an acceptable first-pass well trajectory has been generated. While the use of three-dimensional visualization tools to screen target locations is not uncommon, in many cases this step is bypassed because of the insufficiency of the data.
The selected target points and in some cases a screening-level well trajectory are given to the drilling engineer for more detailed well design and analysis. Analyses include well bore stability, torque, drag and the like. Moreover, these analyses may involve an understanding of the rock and fluid properties along the trajectory. The rock and fluid property information can come from a wide variety of sources including nearby well bores and predictive models, but it is typically difficult for drilling engineers to obtain and input into their analysis software. In addition, the rock and fluid information is often stored in drilling engineering software in a way that makes it well trajectory specific. In such a case the engineer can only reuse the information to a very limited extent when evaluating a new well design. Also, if new rock and fluid data becomes available during the time between the well planning stage and actual drilling, the engineer may have to, on a well-by-well basis, update this information for each of the existing planned wells.
In addition to the selection of targets by the geoscientist and well design analysis performed by the engineers, shallow hazard specialists perform additional, often independent, evaluation of the proposed path. This analysis can result in the identification of issues that may also necessitate additional changes to the target location(s), number of targets, or basic trajectory parameters, thereby adding additional iterations and time to design the final well path.
The results of the well design and analysis typically indicate potential issues with the well as originally conceived and may necessitate changes to the target location(s), number of targets, or basic trajectory parameters. Changes may be made by the geologist and the targets/trajectory may again be sent to the drilling engineer for analysis; depending on the complexity of the well path and geology, a final trajectory may take multiple iterations and several weeks/months of calendar time. The length of time taken to iterate between target selection and detailed well design can limit the number of scenarios examined and lead to sub-optimal results.
While recent integration of three-dimensional planning methods have improved the efficiency of the target selection and well path planning work processes, significant inefficiencies and challenges remain. The variability of individual reservoir intervals and the complex arrangement of multiple reservoirs within a three-dimensional volume of the earth create an inherent complexity difficult to manage using existing tools. Defining the penetration point(s) or segment(s) for individual wells or groups of wells using a process of iteratively selecting and screening individual target points is inefficient, time consuming and leads to sub-optimal reservoir performance. In addition, creating a well path that maximizes the benefit (for example, the output of hydrocarbon resources, sometimes referred to herein as “payout” or “pay”) by penetrating the most desirable reservoir zones while minimizing risk and cost by avoiding possible drilling hazards (e.g. shallow gas sands, faults and the like) while at the same time meeting engineering design specifications requires the integration of numerous multi-dimensional and multi-disciplinary data types.
The amount and complexity of the data to be analyzed and visualized exceeds the capacity of the user and the integration capabilities of current visualization systems. For example, available data may include numerous volumetric representations of the area including seismic data and its derivatives and reservoir or full-earth models representing rock or fluid property variations. Each of these volumes is typically of much greater lateral and vertical extent than the relatively small volume of the subsurface relevant during target selection and well trajectory evaluation. Currently, geologists and engineers may generate a number of display-types to integrate as much data into the evaluation and selection process as possible.
Even with these methods the visualization and analysis of relevant data for target selection and well path design or analysis is extremely difficult and time consuming. Because drilling target selection and the evaluation of resulting well trajectories is a highly iterative process, the use of three-dimensional subsurface volumes for the purpose of drilling target selection and well path design and evaluation has so far been relatively limited. In cases where geologists and engineers do use three-dimensional subsurface volumes for the purpose of drilling target selection and well path design, the amount of time involved in setting up the desired displays limits the number of target combinations/trajectories evaluated. As a result, a significant amount of time is spent inefficiently and the final selected targets and well trajectories may be sub-optimal. An improved system and method of planning a drilling operation is desirable.